Internal combustion engine



June 30, 1942. R, R|CARD0 2,288,326

INTERNAL COMBUSTION ENGINE Filed May 2l, 1940 3 Sheets-Sheet l i F' n' ID y C\E u cI B\5 R2 R' "IK: 3 A 4 p2 Q :u A2 L 1:12:35: i2 Q] l. A3

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INTERNAL QOMBUSTION ENGINE Filed May 2l, 1940 5 Sheets-Sheet 2 Fig. 3.Fig. 4. Fig. 5.

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INTERNAL COMBUSTION ENGINE Filed May 2l, 1940 3 Sheets-Sheet 3 57 m M,9m

H. R. RICARDO 2,288,326 y Patented June 30, 1942 INTERNAL COMBUSTIONENGINE Harry Ralph Ricardo, London, England Application May 21, 1940,Serial No. 336,450 In Great Britain June 1, 1939 (Cl. 12S-65) i 20Claims.

This invention relates to the control of interf nal combustion enginesoperating on the twostroke cycle and with compression ignition and hasfor its object to provide a method and means for effecting ysuch controlwhen an engine is running under idling conditions. The expressionidlingf is here used as designating the condition when the engine isrunning under no load and the fuel charge is reduced below that fornormal running under load, as for instance when.

the engine is in a motor road vehicle and the latter is stationary. y

The present invention is more particularly applicable to highspeedenglnes falling in the abovemen'tionedcategory which have thefollowing features. One or more exhaust ports in the head of thecylinder and scavenging ports in the wall of the cylinder which areuncovered by the piston therein towards the end of the outstroke,passages through which the scavenging air dows leading to these portsfrom a scavenging air belt to which air is delivered by a displacerpump. Such a pump gives a phased supply of scavenge air to the cylinderas distinct from the supply of air delivered' from a rotary blower. Theinvention may, however, be used with an engine in which a rotary blower4delivers an unphased supply of scavenging and charging air to thecylinder. It is also applicable to engines having opposed pistons.

In a two-stroke cycle engine of the above.

mentioned type owing to the large port area required for the scavengingair the closing of the inlet ports takes place late and the effectiveratio of compression is low as compared with an engine operating on thefour-stroke cycle. At low revolution speeds the pressure of the retainedcharging air in the cylinder when the inlet ports have just been closedis liable to be at or about that of the atmosphere and its temperaturehas not been raised appreciably by compression. On the other hand atrelatively high revolution speeds the charging air pressure issubstantial and moreover its temperature has been raised by compressionin the scavenge pump or blower before the inlet ports-are closed. Henceat low speeds there is in the cylinder relatively cold air whosepressure is not appreciably above that of the surrounding atmosphere atthe moment of the closingof the inlet ports, but at high speeds there isheated air whose pressure is considerably above atmospheric pressure atthe coinmencement of compression by the working piston. As a lresultthere tends to be a large difference in both the final compressiontemperature and pressure as between high and low speeds. Since bothtemperature and pressure exert a powerful influence on the rapidity andcompleteness of combustion, it follows that the combustion conditionsmust vary widely as between high and low speeds. This widediiferencebecomes most apparent when the engine is idling at low speeds and noload when, in addition to low temperature and pressure, the internalparts, and more particularly any heat-insulated member when such isemployed, are relatively cool. Under these conditions combustion tendsto become sluggish and incomplete.

When an internal lcombustion engine operatingon the two-stroke cycle andwith compression ignition is idling, and running under the conditionindicated above, that is to say under no load and with the fuel chargereduced below that for normal running under load, according Vto thisinvention the pressure and temperature of the air retained in thecylinder when the inlet ports are closed are so varied that thispressure and temperature then tend to rise at least to the pressure andtemperature existent at the same stage in the cycle when the engine isunder load and running at higher speed. This variation of the pressure'and temperature of the air retained in the cylinder is effected byobstructing in some degree, that is to a greater or less extent; theoutflow of the exhaust gases from the cylinder. Conveniently the meansby which and the manner in which the outilow of the exhaust gases isobstructed when the idling conditions indil cated above are established,will bring about automatically the effect which it is desired to obtainby such gas-obstruction.

In an engine of the above-mentioned type having one or morevalve-controlled exhaust ports in the head of the cylinder the outflowof the exhaust gases from thev passage leading from such port or portsis obstructed to a greater or less extent when the engine is idlingunder no load and the fuel charge is reduced below that for normalrunning under load, the control of the obstruction of the outflow of theexhaust gases being effected by means and in a manner which, when theidling conditions indicated are established, will `automaticallybringabout the gas-obstruction and produce the desired eiIect, namely tocause a rise in the pressure and temperature of the air in the cylinderwhen the inlet ports are closed.' The automatic actuation of the meansby which the gasfobstruction is effected may be controlled by or inaccordance with the speed of the engine. It is desirable by which it iscaused to bring about the extent ot obstruction required at diil'erenttimes may vary. For example this body or member may have a streamlineform and be mounted so as to'be movable along and withinthe exhaustpassage, or towards and into the outer oriilce or mouth of this passage.The internal formation of this passage considered both in the transverseand longitudinal directions adjacent to the place where this body isdisposed is determined so that the desired obstruction to gas flowthrough the passage will beV effected as the body or member is moved inone directionand this obstruction will be lessened as the member ismoved in the opposite direction, As indicated above, in place of beingdisposed actually within 4 with such a known arrangement suitable meansthe. exhaust gas passage, the movable member may be arranged adjacent tothe external orince or mouth of the exhaust manifold or outlet, If

then the member is moved into this mouth it will bring about the desiredvariable obstruction as the gases are about to leave .the exhaustpassage. Again the obstruction may be effected 'by movement of a valveof suitable form disposed in the exhaust passage.

It is preferable that the obstructing body or member or valve should bespring-loaded or yieldingly mounted or actuated in such a way thatin theevent of any failure of the means by which the actuation of this memberis eii'ected, the risk of.

dangerous pressures developing in the engine will beobviated. x

In the case of such an obstruction being constituted by a body ofstreamline or other form as is indicated above, the movement of thisbody in a direction away from the gas outlet, in order to reduce theexhaust gas pressure on the inner side of the outlet, may be effected bya mechanica .l linkage or by a hydraulic or pneumatic relay. A spring orsprings, or in some cases the force of gravity is then relied on toeffect the movement of the obstructing body in the opposite orobstructing direction. It maybe desirable to arrange that a suitabledelay is imposed on the unthrottling action of the obstructing member,that is its movement which tends to lessen the obstruction causedthereby.

Various means may be adopted to eiect the control and actuation of thelgas-obstructing member. Thus this control may be associated more orless `directly with the speed of the engine. For instance movementsderived from a centrifugal governor or from a device actuated forbringing about the desired control and move ment of the obstructingmember in theexhaust gas outlet. In a known method of governing orcontrolling the power ofthe engine, a manually 'operated throttle isdisposed in the air intake manifold and the variations in pressure onthe higher speed by some external means such as an l electric motor orif, through being still connected to the transmission it is overrun,then in order to maintain the same depression in the manifold as existedwhen idling" it is necessary to open slightly the air controllingthrottle, and within certain limits, the higher the speed at which theengine is "matured," the more the throttle has to be moved towards theopen position in order to maintain the same depression in the manifold.

From this it will be apparent that the position of the throttlecontrolling the air supply is related to the speed at which the engineis being' motored, and consequently it becomes possible to make use ofthe various positions of the air controlling throttle to control alsosay a hydraulic relay as above described by means of which movement isimparted to the obstructing body or member which will effect thevariation in the pressure of the exhaust gases in thev exhaust manifoldand of the retained charging air in the cylinder. Y

The present invention is to be differentiated from a known arrangementin which for the purpose of carrying an overload the exhaust from anengine operating on the two-stroke cycle is obstructed or "strangledwhile simultaneously the quantity of the charge supplied to the cylin-Ider is increased. This strangling was arranged to produce a superchargedcondition in the cylinder when carrying an overload. On the other handthe obstruction of the outiiow of exhaust gases in the manner and by themeans comprised in the present invention is, as stated above, for thepurpose of ensuring satisfactory running of the engine under idlingconditions. It may be remarked, however, that the present rylng anoverload in conjunction with the by changes in the pressure of thecirculation of A operated air throttle are utilised to govern the fuelpump and thereby vary the quantity of fuel vdelivered to the engine,there may be combined strangling procedure described above. Such acombination of the knownstrang1ing" and the present improvement may becarried out fon example somewhat'in the following manner where theengine is employed for the propulsion of a motor road vehicle. 'Iheaccelerator pedal of the vehicle for normal loads is arranged so that`it will come up against a resilient stop which will conditions whetherthis devicefcomprises a body disposed in or at the mouthof the exhaustpassage or if it is a throttle disposed in that passage or alternativelya separate and additional ob' transverse and normal to the crankshaftaxis views showing positions of showing one construction of internalcombustion engine operating on the two-stroke cycle with compressionignition provided with the present invention.

.Figure 2 ls a diagrammatic perspective view of an engine showing thearrangement of the apparatus described moreparticularly with referenceto Figure 1.

Figures 3, 4 and 5 are sectional diagrammati av control cock describedhereunder.

Figure 6 is a diagrammatic perspective view similar to Figure 1 butillustrating an alternative method-ofl controlling the movements of "theexhaust-'gas-obstructing member.

i The internal combustion engine operating with compression ignitionshowniln Figure 1 as having the present invention applied theretocomprises the lfollowing principal features.

In thecyllnder A is a liner A1 in the wall of which are 4ports A2through which scavenge air enters from a scavenge air belt A. The portsA2 are positioned where they will be uncoveredA by the piston B towardsthe end of its outstroke In the head of the cylinder is a combustionchamber C of the open type, that is to say the communicating openingbetween this chamber and the cylinder A is a "mouth of substantial size.The chamber C is centrally situated with respect to the cylinder Ahaving a contour which is a figure of revolution about the cylinderaxis. The diameter of the annular lip C1 vround the mouth of the chamberC ls somewhat less than the maximum diameter of the chamber. Into,

this chamber there is forced by the pistonat the end of its compressionstroke as much of the ,air charge as ls practicablerfrom thevconstructlonal point of view.

Centrally situated in the inner Wall of the combustion chamber C andhence opposite to the mouth of this chamber, is an exhaust port D inwhich is situated a poppet valve D1. This valve is actuated by anoverhead camshaft E. `The exhaust port D f opens into a passage whichleads lnto the exhaust manifold F, the outlet from this manifold 4beingby way of an opening F1 leading to a passage 1i'a ln communication withthe atmosphere. .l

The cylinder A is mounted on a casing G e closing the crankshaft andhaving below lt an oil sump G1. On one side of the casing G is a pumpcylinder H which projects laterally with its axis at right angles to theplane in which lies the axis of the cylinder and the axis of thecrankshaft J. The horizontal plane in which lies the axis of the -pumpcylinder is situated somewhat 4below the axis of the crankshaft J. Inthe cylinder H is a piston H1 which-is reclprocated on a rod H whoseends are fixed at the ends of the cylinder H, movement being impartedtothe piston H1 by a link IH3 which connects lt to the big-end ofthelconnecting rod B1 Extending from the cylinder H to the scavenge airbelt Al is a transfer passage K in which is a rotary valve K1. Thisvalve controls on the one hand the intake of air to the cylinder H froman air inlet pipe K and on the other hand. the deliveryJ of air by thepump through tiie passage K to the scavenge air belt A. Owing to thephasing relation between the movements of the work- A lng piston ,B andthe piston H1 of the pump and by reason of the timing effected by therotary valve K1, air under a pressure above the mean scavenging pressureis trapped in the scavenge member M towards the opening F1.

air belt A3 and the transfer` `passage K between the valve K1 and thatbelt.

The fuel injectorrwhich ls not shown in the drawings but is connected tothe fuel pump L by a pipe L1 delivers fuel into the combustion chamber Cthrough the side wall of that chamber.

In the above-described engine the outflow of exhaust gases through theport D and passage F is obstructed under the idling" conditionsVindicated by a member M which can be moved towards and into or awayfrom the opening F1 through which the exhaust gases pass from themanifold F. The obstructing member M is mounted at the upper end of arod M1 on the lower end of which, is a piston M2 which can reciprocatein a cylinder N situated inthe cil sump G1. The rod M1 is guided and canslide vertically in bearings M1, M4 and it is acted or. above thecylinder N by a coiled spring O situated between a collar M5 on the rodM1 and the upper and closed end N1 of the cylinder N whose lower end isopen. This spring O tends to raise the rod M1 and move the obstructingMovement in the opposite direction is caused by oil pressure in thecylinder N above the piston M11 this j'pressurel being conveyed througha pipe P and passage P1 from the lubricating oil system of the engine.In a body P2 ln the upper part of the oil passage P1 ls a rotatable cockQ whose spindle Q1 -ls connected to the spindle R of a butterfly valveR1 disposed in some convenient position in the moved into and maintainedin a position clea" of the opening F1 so as to allowthe exhaust gases toflow freely through this opening to the atmosphere. If, however, the oilpressure in the pipe` P is cut oil' the spring O` will cause the pistonM2 to move upwards carrying with it the obstructingr member M which willthus' be moved towards or into the exhaust gas opening F1. This upwardmovement of the piston M2 becomes possible since thev oil in thecylinder N above the piston can escape through the leak-oil' hole M8 inthe piston after closing of the cock Q. This obstruction by the member Mwill thus occur when the engine ls running under the idling conditionsindicated. The obstruction of the outflow of exhaust gases will resultin a back pressure in the cylinder A which will cause a rise in thepressure and temperature of the air retained in the cylinder after thescavenge air ports Az have been closed by the piston B on itscompression stroke. e

The oil pressure in the pipe Pv and in the cylinder N above the pistonM2 is controlled by rotation of the cock Q when the air throttle valveR1 is turned. If the lever R is moved in a direction ltending to closethe throttle valve R1, not only will the cock Q be turned towards itscloset position, shown ai I in Figure a, but the depression caused inthe air inlet passages K2, K3 acts in a known manner on the fueldelivery pump L ln such a way as to reduce the supply of fuel deliveredinto the combustion chamber C, for examplas disclosed in the Britishpatent to Junkers,No. 286,7Q7.

tle R1 is set to cause the depression which will give the fuel supply`required for the no load idling condition the cock Q will be closed.Thus the oil pressure above the piston M2 will be cut off when thethrottle valve R1 is closed `ousii'y been"prposed as mentioned above.

to the extent that it will normally be closed when the engine is tocontinue running under; idling conditions with no load.

valve R1 and the cock Q in the casing P11 for exercsing thediscriminating control mayl be actuated by a foot pedal S through a linkS1 connected to the lever R2.

In Figure 2 there is shown how the throttle trolled from the foot pedalS by movement,`

Y supply to the engine.

By suitable operation of the cock Q 'the obstruction or "strangling ofthe outow oi' the exhaust gases maybe caused to occur at suc, times asto produce a supercharged conditie in the cylinder when theengine iscarrying an" overload. Such a use of strangling has previ- Fig.- ures 3,4 and 5 show different positions of the cock Q corresponding to diierentengine conditions and the effects' then to be produced. The

oil flow under pressure through the passage P1 to the cylinder N is inthe direction indicated by the arrow in each of these figures.

In Figure 3 are shown three principal positions Ywhich may be occupiedby the lever R2 by means of which the cock is moved. The position I isthat when the engine is idling and the cock Q is moved to close thepassage P1 with the result that there is no pressure above the piston M2and consequently the spring O will move 'the obstructing member Mtowards or into the exhaust gas outilow opening F1.

During normal running of the enginethe throttle lever R2 will be movedbetween the p0- sitions I and II. In the latter position the cock Q willbe as shown in Figure 4 this position corresponding to full loadconditions. The pressure of the lubricating oil system can now actthrough the pipe P on the piston M2 and cause the obstructing member Mto move clear of the opening F1 leaving a free outflow for the exhaustgases.

If owing to an overload it is desired to produce a superchargedcondition by strangling combined with full throttleand fuel supply, the.

lever R2 is moved beyond the position II into the position III wherein,as shown in Figure 5, the cock Q has again closed or almost closed thepassage P1 with the same eiect on the movement in Figure 5 while thelthrottle valve R1 will remain fully open.

Referring to Figure 6 there is here shown an arrangement by means ofwhich the liquid pressure acting on and imparting movement to thegas-obstructing member M is controlled automatically in accordance withthe speed of the engine. In this arrangement the engine is conthrough alink S2 of the rack member L2 which in the fuel pump L controls andvaries the'fuel In an engine thus controlled there is no throttle valvein the air intake K3 as in the arrangement previously described. Themovement of the cock in the cast` ing P1 which controls the ow of oilunder pres,

sure through the pipe P to the cylinder N where `it acts through the rodM1 on thLgas-obstructing member M, is effected automatically in thefollowing way.- Arranged on or driven from the engine crankshaft is agovernor of some suitable type. This governor here. showndiagrammatically comprises a shaft TA through which it is fromy the.engine crankshaft this shaft ergona .sleeve'T'ladapted to. be movedalng=the shaft'T bythe weights T2 when these of the cock in the casingP2 is a lever Q3 connected by a link Q4 to a lever U2 on the rock Whenthe engine is running normally at speed the governor weights 'I2 fly outand through the sleeve T1 cause the lever Q3 of the control cock to beturned clockwise as seen in Figure 6. This moves the cock Q intosubstantially the position II in which itis shown in Figure 4. If nowthe speed of the engine falls to the speed at which itwould ordinarilyrun when idling and disconnected from the transmission, the governorweights 'I'2 will swing in towards the shaft T and such movement will beimparted through the rock shaft'U1 to the cock spindle Q2 that the cockwill move substantially into the position I in which it is shown inFigure 3. The hydraulic pressure operative in the cylinder N on thegasobstructing member M will then be cut off so that the 'spring actingagainst this hydraulic pressure on the gas-obstructing member will causethe-latter to obstruct to a, greater or less extent the outflow ofexhaust gases from the exhaust gas manifoldI F.

.If now by movement of the pedal S and the fuel-controlling. rack VIfthefuel supply to the .engine is increased and the speed of the latter inofthe obstructing member M as when the lever A Rz'and cock Q were in theidling position I as shown in Figure 3. l

To enable the overload strangling eifect for as once more to cause thehydraulic pressure to act in the cylinder N and withdraw theobstructmanifold F.

' supercharging to be obtained, the spindle Q1 of cock can vbe continuedinto the position III shown It will be noted that in this arrangementwhile theffmovements of the gas-obstructing member M take placeautomatically and in accordance with the speed of the vengine so thatobstruction to the outflow of exhaust gases will be effected andthedesired, end attained when the'engine is running swig radially inaccordance with the speed of gases pass from the cylinder into anexhaust manifold and thence through an opening to the atmosphere, amember mounted adjacent to the said exhaust gas outlet opening andmovable into positions wherein it will obstruct in some degree theoutflow of exhaust gases through the said opening, said member-beingconstructed and arranged for movement out of such obstructing p ositionsin response to application thereto of excessive exhaust gas pressures,yielding means tending automatically to.;move the said member in adirection which will cause itto obstruct the exhaust gas outflow, andpositively acting means automatically operable in response to variationlin operating conditions for moving the said member in a direction whichwill reduce obstruction thereby to the gas utilow as set forth.

2. In an internal combustion engine operatnition, the combination oi' atleast one valvecontrolled exhaust port through which the exhaust gasespass from the cylinder into an exhaust manifold and thence through anopening to the atmosphere, a member mounted adjacent to the said exhaustgas outlet opening and movable into positions wherein it will obstructin some degree the outflow ci exhaust gases through the said opening,said member being constructed and arranged for movement out of suchobstructing positions in response to application thereto of excessiveexhaust gas pressures, yielding means tending automatically to move thesaid member in a direction which will cause it to obstruct the exhaustgas outilow, and hydraulically actuated means for moving the said memberin a direction which will reduce obstruction thereby to the gas outow asset forth.

3. In an internal combustion engine operating on the two-stroke' cyclewith compression ignition, the combination of at least onevalve-controlled exhaust port through which the exhaust gases pass fromthe cylinder into an exhaust manifoldI and thence through an opening tothe atmosphere, a member mounted adjacent to` the said exhaust gasoutlet opening and movable into positions wherein it will obstruct insome degree the outflow of exhaust gases through the said opening, saidmember being constructed and arranged for movement out of suchobstructing positions lin response to application thereto of excessiveexhaust gas pressures, spring-actuated means to move the said member ina direction which will cause it to obstruct the exhaust gas outflow, andhydraulically actuated means for moving the said member against theaction of the spring in a direction which will reduce obstructionthereby to the gas outflow as set forth.

4. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, the combination of at least onevalve-controlled exhaust port through which the exhaust gases pass fromthe'cylinder intofan exhaust manifold and thence through an opening tothe atmosphere, a member mounted adjacent to the said exhaust gas outletopening and movable into ing on the two-stroke cycle with compressionigl positions wherein it will obstructin some degree the outow ofexhaust gases through the said opening, means tending automatically tomove the said member in a direction which will cause it to obstruct theexhaust gas outflow, and a member acted on and movable by hydraulicpressure derived from the engine lubricating system this member beingconnected to and movable by this hydraulic pressure with the saidgas-obstructing member in a direction which will reduce. obstructionthereby to the gas outilow as set forth.

5. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, the combination of at least onevalve-controlled exhaust port through which the exhaust gases pass fromthe cylinder into an exhaust manifold and thence through an opening tothe atmosphere, a member mounted adjacent to the said exhaust gas outletopening and movable into positions wherein it will obstruct in somedegree the outflow of exhaust gases through the said opening, meanstending automatically to move "'the said member in a direction whichwill cause it to obstruct the exhaust gas outflow, a member acted on andmovable by hydraulic pressure derived from the engine lubricating systemthis member being connected to and movable by this hydraulic pressurewith the said gas-obstructing member in a direction which will reduceobstruction thereby to the gas outow, and a cock in the hydraulicpressure system with means for moving this cock to control thisp'ressureand the movement it imparts to the gas-obstructing member as set forth.

v6. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, the combination of at least onevalve-controlled exhaust port through which the exhaust gases pass fromthe cylinder into an exhaust manifold and thence through an opening tothe atmosphere, a member mounted adjacent to the said exhaust gas outletopening and movable into positions where in it will-obstruct in somedegree the outiiow of exhaust gases through the said opening,spring-actuated means to move the said member in a direction which willcause it to obstruct the exhaust gas outflow, a member acted on andmovable by hydraulic pressure derived from the engine lubricating systemthis member being connected to and movable by this hydraulic pressurewith the said gas-obstructing member in a direction opposite to that inwhich the gasobstructing member is moved by the said spring, and a cockin the hydraulic pressure system with means for moving this cock tocontrol this pressure and the movement it imparts to the gasobstructingmember as set forth.

7. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, the combination of at least onevalve-controlled exhaust port through which the exhaust gases pass fromthe cylinder into an exhaust manifold and thence through an opening tothe atmosphere, a member mounted adjacent, to the said exhaust gasoutlet opening and movable into positions wherein it will obstruct insome degree the outflow of exhaust gases through the said opening, acylinder with a piston movable therein and connected to the saidgas-obstructing member, means tending automatically to move the pistonand the said member in adirection which will cause the member toobstruct the exhaust gas outflow, and a pipe connection between theengine lubricating 'system and the said cylinder through. which pipingou under pressure can act in the cylinder on the piston and move it andthe said gas-obstructing memto the gas outow, and a cock in the oilpassage ber in a direction which will reduce obstruction thereby to thegas outow as set forth.

8. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, the combination of at least onevalve-controlled exhaust port through which the exhaust gases pass fromthe cylinder into an exhaust manifold and thence through an opening tothe atmosphere, a member mounted adjacent to the said exhaust 'gasoutlet opening and movable into positions wherein it will obstruct insome desaid cylinder through which piping oil under pressure can act inthe cylinder .on the piston and move it and the said gas-obstructingmember in tion to the gas outow as set forth.

9. In an internal combustion engine operating on the two-stroke vcyclewith compression ignition, the combination of atleast onevalve-controlled exhaust port through which vthe exhaust gases pass fromthe cylinder into an exhaust manifold and thence through an opening tothe atmosphere, a member mounted adjacent to the said exhaust gas outletopening and movable' into positions wherein it will obstruct in somedegree the outflow of exhaust gasesthrough the said opening, a cylinderwith, apiston movable therein. and connected to the said gas-obstructingmember, a spring acting on the said member to move the piston and themember in a direction which will cause the member to obstruct theexhaust gas outflow, a pipe connection between the engine lubricatingsystem and the said cylinder through which piping oil under pressure canact in the cylinder on the piston and move it and the saidgas-obstructing member in a direction opposite to that inwhich it ismoved by the said spring thereby reducing the obstruction to the gasouow, and means controlling the oil pressure in the said cylinder andthe movement it imparts to the gas-obstructing member as set f orth.

v10. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, the combination of at least one valvev to theatmosphere, a member mounted adjacentto the said exhaust gas outletopening and movhaust gases -pass from the cylinder into an exleading tothe said cylinder with means for moving this cock to control the oilpressure acting in the cylinder and the movement it imparts to lthegas-obstructing 'member as set forth.

l1. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, the combination of at leastone'valvecontrolled exhaust port through which the exhaust gases passfrom the cylinder into an exhaust manifold and thence through an openingto the atmosphere, a member mounted adjacent to the said exhaust gasoutlet opening and movable into positionswherein it will obstruct insome degree the outflow of exhaust gases through the said opening,spring-actuated means to move the said member in a direction which willcause it to obstruct Athe exhaust gas outflow, means for moving the saidmember against the action of the spring in a direction which will reduceobstruction thereby to thegas outiiow, means controlling the said meanswhich move the said member against the action of the spring, and

means for controlling the supply of air and fuel 12. In an internalcombustion engine operating on the two-stroke cycle with compressionignition, the combination of at least one Valvecontrolled exhaust portthrough which the exhaust manifold and thence through an opening to theatmosphere, a member mounted adjacent to the said exhaust gas outletopening and movable into positions wherein it will obstruct in somedegree the outflow of exhaust gases through the said opening, a cylinderwith a piston movable therein and connected to the said gas-obstructingmember, a spring acting on the said member to move the piston and themember in a direction which will cause the member to obstruct theexhaust gas outflow, a pipe connection between the engine lubricatingsystem and the said cylinder through which piping oil under pressure canact in lthe cylinder on the piston and move it and the saidgas-obstructing member in a direction opposite to that in which it ableinto positions wherein it Iwill obstruct in some degree the outflow ofexhaust gases through the said opening, a cylinder with a piston movabletherein and connected to the said gas-obstructing member, a springacting on .the said vmember tc move the piston and the member in amovement it imparts to the gas-obstructing member, and means forcontrolling the supply of air and fuel respectively to the workingcylinder this control being associated withthe said means which controlthe oil pressure in the said cylinder as set forth.

13. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, the combination of at least onevalvecontrolled exhaust port through which the exhaust gases pass from.the cylinder into-an exhaust manifold and thence through an opening tothe atmosphere, a member mounted adjacent 'member-'gto move the pistonand the member in a direction whichwill cause the member to obstruct theexhaust gas outflow, a pipe connection between the engine lubricatingsystem and-the message said cylinder through which piping oil underpressure can act in the cylinder on thepiston and move it `and the saidgas-obstructing member in a' direction opposite to that in which it ismoved by .the said spring thereby reducing the obstruction to the gasoutflow, a cock Ain the oil passage leading to the said cylinder withmeans formoving this cock to control the oil pressure acting in y)thecylinder and the movement it imparts to the gas-obstructing member, andmeans for controlling the supply of air and fuel respectively to theworking cylinder such means being associated with the means for movingthe said cock controlling the oil pressure as set forth.

14. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, the combination of a cylinder, at least onevalve-controlled exhaust port in the headA of this cylinder, an exhaustmanifold into which Y' the gases from this port pass and whence they canescape through an outlet opening to the atmosphere, a member mountedadjacent to the said exhaust gas outlet opening and movable intopositions wherein it will obstruct in some degree the outow of exhaustgases through the said opening, spring-actuated means to move the saidmember in a direction which will cause it to obstruct the exhaust gasoutflow, a member acted on and movable by hydraulic pressure derivedfrom the engine lubricating system this member being connected to andmovable by this hydraulic pressure with the said gas-obstructing memberin a direction opposite to that in which the said gas-obstructingmemberv is moved by the said spring, and a cock in the hydraulicpressure system with means for moving this cock to control this pressureand the movement it imparts to the gas-obstructing member as set forth.

15. In an internal combustion engine operating on the two-stroke .cyclewith compression ignition, the combination of a cylinder, at least onevalve-controlled exhaust port in the head of this cylinder, an exhaustmanifold into which the gases from this port pass and whence they canescape through an outlet opening to the atmosphere, a membermountedadjacent to the said. exhaust gas outlet opening and movable intopositions wherein it will obstruct in some degree the outflow of exhaustgases through the said opening, a cylinder with a piston movable thereinand connected to the said gas-obstructing member, a spring acting on thesaid member to move the piston andthe member in a direction which willcause the member to obstruct the exhaust gas outflow, and a pipeconnection between the engine lubricating system and the said cylinderthrough which piping oil under pressure can act in the cylinder on thepiston and move it and the said gas-obstructing member in a directionopposite to that in which it is moved by the said spring therebyreducing the'obstructlon to the gas outflow as set forth.

16. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, the combination of a cylinder, at least onevalve-controlled exhaust port in the head of this cylinder, an exhaustmanifold into which the gases from this port pass and whence they canescape through an outlet opening to the atmosphere, a member mountedadjacent to the said exhaust gas outlet opening and movable intopositions wherein it will obstruct in some degree the outflow of exhaustgases through the said opening a cylinder with a piston movable thereinand connected to the said gas-obstructing member, a-spring actingv onthe said member to move the piston `and the member in a direction whichL will cause the member to obstruct the exhaust gas outflow, a pipeconnection between the engine lubricating system` and the said cylinderthrough which piping oil under pressure can'act in the cylinder 0n thepiston and move it and the said gas-obstructing member in a directionopposite to that in which it is moved by the said spring therebyreducing the obstruction to the gas outflow, and means controlling theoil mosphere, a member mounted vadjacent to theA said exhaust gas outletopening and movable into positions wherein it will obstruct in somedegree the outflow of exhaust gases through the said opening,spring-actuated means to move the said member in a direction which willcause it to obstruct the exhaust gas outflow, means for moving the saidmemberA against the action of the spring in a direction which willreduce obstruction thereby to the gas outflow, means controlling thesaid means which move the said member against the action of the spring,and means for controlling the supply of air and fuel respectively to theworking cylinder this control being associated with the said means whichcontrol the movement of the gas-obstructing member as set forth.

18. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, the combination of a cylinder, at leas-t onevalve-controlled exhaust port in the head of this cylinder, an exhaustmanifold into which the gases from this port pass and whence they canescape through an outlet opening to the atmosphere, a member mountedadjacent to the said exhaust gas outlet opening and movable intopositions wherein it will obstruct in some degree the outflow of exhaustgases through the said opening, a cylinder with a piston movable thereinand connected to the said gas-obstructing member, `a spring acting'onthe said member to move the piston and the member in a direction whichwill cause the4 member to obstructthe y exhaust gas outflow, a pipeconnection between the engine lubricating system and the said cylinderthrough which 'piping oil under pressure can act in the cylinder on thepiston and move it and the said gas-obstructing member in a. directionopposite to that in which it is moved by the said spring therebyreducing the obstruction to the gas outflow, a cock in the oil passageleading to the said cylinder with means for moving this cock to controlthe oil pressure acting in the cylinder and the movement it imparts tothe gasobstructing member, and means for controlling the supply of airand fuel respectively to the working cylinder such means beingassoci-ated withthe means for moving the said cock controlling the oilIpressure as set forth.

19. In an internal combustion engine operating on the two-stroke cyclewith compression ignition, theV combination of at least onevalvecontrolled exhaustl port through which the exi tion which willcauseit to obstruct the exhaust gas outflow, and positively acting meansactuated and controlled automatically in accord' anceI with the speed oftlffe engine for moving the said member against the action of the springin a direction which will reduce obstruction thereby to the gas outow asset forth.

20. In an internal combustion engine yoperat- I ing on the two-strokecycle with compression ignition, the combination of at least onevalvecontrolled exhaust port through which the exhaust "gases pass fromthe cylinder into an exhaust manifold and thence through an opening tothe atmosphere, Va member yieldingly mounted opposite to the saidexhaust gas outlet opening 'towards and away from which it is movable toposition it where it will obstruct in some degree the outflow of exhaustgases -through the said opening, the yielding mounting for this membertending automatically to move it towards the said opening and cause itto obstruct the gas outflow but then permitting undue pressure ofexhaust gases in the manifold to move the obstructing member and allowthese gases to escape, and positively acting means automaticallyoperable in response to variation in operating conditions for moving thesaid member away from the said opening, thereby reducing the obstructionto the gas-outflow as set forth.

HARRY RALPH RICARDO

